The description 'decreases platelets' ability to form a clot' is most consistent with which condition?

• A. Thrombocytopenia
• B. Hemophilia A
• C. Von Willebrand disease
• D. Sickle cell disease

Answer: (A)

Clot formation starts with platelets forming a plug at the site of injury (primary hemostasis). If there are fewer platelets available, or if their function is impaired, there aren’t enough platelets to adhere and aggregate, so the initial platelet plug is weak or missing. That’s precisely what happens in thrombocytopenia—a decreased platelet count leads to impaired ability to form a clot.

Hemophilia A, by contrast, is a deficiency of a coagulation factor (factor VIII) in the coagulation cascade, so bleeding tends to occur due to a problem in forming the fibrin clot after the plug is already started, not because the platelets are reduced. Von Willebrand disease affects platelet adhesion because of defective or deficient von Willebrand factor, but platelet count is usually normal, and the core issue is adhesion rather than a shortage of platelets. Sickle cell disease involves abnormal red blood cells and vaso-occlusion, not a primary defect in platelet quantity or the initial platelet plug formation.